Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$158.80	9.603%	$174.0496	$174.05	$174.05	$174.00
Purchase #2	$236.46	7.628%	$254.4972	$254.50	$254.50	$254.50
Purchase #3	$197.90	12.236%	$222.115	$222.12	$222.10	$222.10
Purchase #4	$229.47	11.286%	$255.368	$255.37	$255.35	$255.40
Purchase #5	$32.69	6.653%	$34.8649	$34.86	$34.85	$34.90
Purchase #6	$36.44	3.660%	$37.7737	$37.77	$37.75	$37.80
Purchase #7	$151.57	9.855%	$166.5072	$166.51	$166.50	$166.50
7 purchase totals =	$1,043.33		$1,145.1756	$1,145.18	$1,145.10	$1,145.20